Authorities are investigating the death of a 57-year-old man who'd been serving murder and other sentences at a state prison in southeast Nebraska.

The Nebraska Department of Correctional Services says Ronald Fort died around 10:20 p.m. Tuesday at Johnson County Hospital in Tecumseh. Officials say Fort was in his Tecumseh prison cell when a medical incident occurred, so he was taken to the hospital.

The department says Fort had been serving a combined sentence of nearly 32 years for convictions on second-degree murder, manslaughter and a weapons crime.

Under state law, a grand jury conducts an investigation whenever anyone dies in custody or while being arrested.